(1) 松尾硫黄鉱体の下盤側にあるモンモリロン石帯のさらに外側下盤に,それに接して発達する帯緑黒色安山岩は,従来からプロピライトとよばれてきた.この中の緑色鉱物は複輝石安山岩中の斜方および単斜輝石,斜長石,石基の一部を交代して現われ,鏡下ではセンイ状,放射センイ状,不規則形,葉片状をなし,クリストバル石や炭酸塩鉱物と共生し,X=帯褐緑色,Z=淡緑灰色の多色性を有し,α=1.56₄,γ=1,59₈,γ-α=0.03₄で,D. T. A.と,X線的資料を加味すると鉄サポー石と考えられ,したがつてこれを含む帯緑黒色安山岩はサポー石化安山岩であることを明らかにした.
(2) よつて硫黄鉱体より下盤外側に向こうにつれて,標式的にはつぎの変質帯が規則正しく配列する.硫黄鉱体→蛋白石明礬石帯→カオリン鉱物帯→モンモリロン石帯→サポー石帯.
(3) サポー石帯は,活発に活動した酸性鉱化剤がしだいに母岩と反応してそあ酸性度を低下し,ついに中性ないし弱アルカリ性の鉱化溶液と化し,その滲透によつて生じたと考える.
(4) 鉱体よりはるかに離れた帯緑黒色安山岩を調べた結果,それはサポー石のほかにカオリン鉱物,緑泥石類,絹雲母などを伴うきわめて複雑なものと考えられ,鉱体を離れるとともに,サポー石化安山岩はかかる複雑な変質鉱物を含む帯緑黒色ないし帯緑黝灰色安山岩に移化すると思われ,これらをかりにプロピライト様岩石と呼称することにした.
(5) 松尾八幡平周辺地区に広大に分布するプロピライト様岩石を生成した変質は広域変質に属し,硫黄鉱体に接して発達する蛋白石明礬石帯よりサポー石帯までの変質作用は,鉱床生成に直結した狭域変質によつて形成されたと考える.

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The Nakatatsu mine, Fukui Prefecture, Japan, is one of the high temperature replacement ore deposits found in limestones of Palaeozoic age. It is one of most productive mines of lead and zinc in Japan.
In this paper some descriptions of the zonal arrangement of skarn, and occurrence and nature of sphalerite are given.
In the Nakatatsu mining district the limestone beds have many fine bands of shale and are intruded by many porphyrite-dykes.
The ore deposition began with skarnization of the limestone bed; in shale and porphyrites the skarnization did not take place to an appreciable extent. Well-defined, zoned skarns occur characteristically near the limestone side as follows:
Limestone; wollastonite-diopside skarn; diopside-garnet skarn; hedenbergite skarn.
Judging from field relations of the occurrence of skarn minerals, the formation of skarn may be divided into the following two stages,
1, Stage of the formation of wollastonite, diopside, and hedenbergite.
2, Stage of the formation of garnet.
Another characteristic feature in skarns of limestone origin is its beautifully banded structure which represents ghost textures of the host rock replaced by the skarns. The banded structure of these skarns is well shown by the arrangement of newly formed lime-silicate minerals.
After the skarnization, quartz-calcite-sulphide mineralization took place in the skarn masses.
From geological observations of the deposit, it is considered that there were no large openings to control sulphide mineralization before sulphide mineralization started and after skarnization. Therefore the path of sulphide-mineralizing solutions was controlled by the skarn rock itself. A part of the hedenbergite skarn zone became the main path of ascending solutions. Sulphide mineralization has occurred through small cracks in the skarn zones, and took place throughout the skarn mass.
The sulphide minerals of the deposit include sphalerite, galena, pyrrhotite and chalcopyrite.
Sphalerite, which is the main sulphide mineral, was examined, by X-ray powder, optic, and spectrographic methods. Its lattice constant was calculated and its Fe-content was estimated.
From the results of these studies, it was found that the Fe-content of sphalerite varies from 3.0% (lattice constant is 5, 413Å) to 9. 5% (5, 423Å). The Fe-content of the sphalerite becomes gradually higher from the outer zone sphalerite (wollastonite diopside zone) to the central zone sphalerite (hedenbergite zone). This variation of Fe-content in sphalerite corresponds well with that of the skarn zones.
The relation between skarnization and sulphide mineralization as described above for the Nakatatsu deposits is very interesting.

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The thermal metamorphism of coal seams by the intrusion of sills or dykes of "don" produced metamorphosed coals of several types such as cinder coal, anthracitic coal ("muen"), and semi-anthracitic coal ("hakuen").This thermal metamorphism did not always occur in the same manner, but instead is characterised by two types of metamorphism based on differences in the nature of the coal.Among these differences the coking power of the coal had the greatest influence on the mode of metamorphism.For this reason the writer has divided the thermal metamorphism of the coal into two types, one of which had stronger coking power and the other with weaker or no coking power.In both types, we can recognize several zones of thermal metamorphism;the mineralogical, petrological, and chemical properties of all are described in detail.
The degree of thermal metamorphism of coal may be best indicated by the values and variations of fuel ratios.It is surprizing, however, that the cinder coal at the contact of coal with the"don"has a fairly low fuel ratio, compared to that of the cinder coals of the outer zones of the contact. This apparent lower fuel ratio may be ascribed to the relatively abundant content of carbonates in the contact cinder coals.So the writer corrected the fuel ratios by recalculating the volatile components, that is by subtracting carbon dioxide in carbonates from the volatile components analysed.The amount of the carbonates have been obtained from the contents of MgO, CaO, and FeO of the analysed ashes.
The temperatures of the thermal metamorphism were estimated by comparison of the fuel ratios in natural coals with those of artificial cokes prepared at definite temperatures.The maximum temperature at the contact was determined to lie between 670 and 700°C.From the maximum temperature, the writer estimated the temperature of the final solidification of magma of the"don" using the equationss and tables of Jaeger; the result shows that it may lie between 700 and 800°C.

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